Michel Foucault (October 15, 1926 - June 26, 1984) was a Frenchphilosopher and "historian of systems of thought". He had an enormous impact on many fields including literary criticism and theory, philosophy (especially philosophy of science in the French speaking world), history, psychoanalysis, history of science especially scientific medicine, and the sociology of knowledge, which he can be said to have transformed altogether.

He is considered a postmodernist and a poststructuralist (though some consider his earlier works, like The Order of Things, to be structuralist - possibly reflecting a lack of distinction at the time). His structuralist or poststructuralist leanings have led others to question the basis of his political activism, a problem he shares with Noam Chomsky, George Lakoff and Jane Jacobs. His work grows out of that of French thinkers on the history of science. Foucault was a remarkably fastidious gatherer of historical evidence, and included many minutiae to support his belief of the historical organization of power.

In his various books, Foucault concentrated on specific social institutions and how they constituted power and control. He also charted their changes in form and practice throughout history. Discipline and Punish dealt with the development of prisons, Madness and Civilization with treatment of the insane, The Birth of the Clinic on the rise of medicine and hospitals, and The Order of Things discussed the sciences. His The History of Sexuality was a three-volume work that was never completed due to his death.

One of his most popular works, Discipline and Punish, looks at the ways in which the overt control through fear used in pre-modern times (public executions and torture, for example) have been generally replaced with covert, psychological controls. Modern society is compared with Jeremy Bentham's "Panopticon" design for prisons, in which a few guards are able to watch many prisoners, while themselves remaining unseen, this is referred to as The Gaze. Foucault also remarks that since the birth of the prison system, prison has frequently been considered to be the only solution for criminal behavior.

The greatest part of Foucault's work is concerned with the relationship between power and knowledge - the sociology of knowledge. For Foucault, "truth" (that is, what functions as truth or is taken as truth in a given historical situation) is produced by the operations of power, and the soul or the human subject is simply a handle for the manipulation by power of bodies. For Foucault, power that is determined through systems of truth could be challenged by appeal to disqualified forms of discourse, knowledge, history, etc., through the privileging of body over abstract intellect, and through artistic self-creation. Power is not formal, according to Foucault, but is the various methods that ingrain themselves by way of social institutions and the positing of a form of truth.

NOTE: definitions of these terms are not rigorous, both due to the difficulty of translation, and the fact that Foucault invented terms often without explaining them, relying on context to explain them, much as real words enter language. Accordingly his use of them may not be easy to correctly apply.